I'm off to Death Valley, Buttercup Valley, Redwoods, San Francisco, L.A. in April. Never been before so couldn't comment.
Finse, Norway is best in March / April (the same time it was filmed in) but the hotel will be booked solid at weekends. You could try the Hostel or nearby towns Geilo / Voss for weekend visits. Midweek visits should be no problem.